Re: dynamic /dev security hole?

[Eric Lammerts]

On Mon, 9 Aug 2004, Marc Ballarin wrote:
> +Q: Are there any security issues that I should be aware of?
> +A: When using dynamic device numbers, a given pair of major/minor numbers may
> +   point to different hardware over time. If a user has permission to access a
> +   specific device node directly and is able to create hard links to this node,
> +   he or she can do so to create a copy of the device node. When the device is
> +   unplugged and udev removes the device node, the user's copy remains.
> +   If the device node is later recreated with different permissions the hard
> +   link can still be used to access the device using the old permissions.

Just an idea for a fix for this problem: If udev would change the
permissions to 000 and ownership to root.root just before it unlinks
the device node, the copy would become useless.

Eric
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